In digital signal processing, many multi-microphone arrangements exist where two or more microphone signals have to be combined. Applications may vary, for example, from live mixing scenarios associated with teleconferencing to hands-free telephony in a car environment. The signal quality may differ among the various speaker channels depending on the microphone position, the microphone type, the kind of background noise and the speaker. For example, consider a hands-free telephony system that includes multiple speakers in a car. Each speaker has a dedicated microphone capable of capturing speech. Due to different influencing factors like an open window, background noise can vary strongly if the microphone signals are compared among each other.